ENDOSULFAN
Method number: |
PV2023 |
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Matrix: |
Air |
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Target Concentration: |
0.1 mg/m3 (TLV time weighted average) |
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Procedure: |
Samples are collected by drawing
known volumes of air through OSHA versatile sampler tubes (OVS-2) containing a glass fiber
filter and two sections of XAD-2 adsorbent. Samples are desorbed with toluene and analyzed
by gas chromatography (GC) using an electron capture detector (ECD). |
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Recommended air volume
and sampling rate: |
60 L at 1.0 L/min |
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Detection limit of the overall procedure (based on the recommended air volume): |
3.4 µg/m3 |
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Status of method: |
Stopgap method. This method has been only partially evaluated and is presented for information and trial use. |
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Date: April, 1988 (final) |
Chemist: Duane Lee |
Carcinogen And Pesticide Branch
OSHA Analytical Laboratory
Salt Lake City, Utah
1. General Discussion
1.1. Background
1.1.1. History of procedure
The OSHA Analytical Laboratory received a set of samples
requesting the analysis of endosulfan from glass fiber filters. Retention and storage
studies on glass fiber filters yielded poor recoveries of endosulfan. Therefore, this
report describes the preliminary validation of a sampling and analytical method using
OVS-2 tubes.
1.1.2. Toxic effects (This section is for information only and should not be taken as the basis of OSHA policy).
Technical endosulfan consists of about four parts of a-cis
isomer, and one part of ß-trans isomer. The a isomer,
which is somewhat more insecticidal, is slowly converted to the more stable ß form at high
temperatures and both isomers are oxidized slowly in air and biological systems and rapidly by
peroxides or permanganates to endosulfan sulfate (Ref. 5.2.). Endosulfan has an acute
LD50 to the rat of 30 mg/kg in alcohol suspension, 70 mg/kg in
aqueous suspension, and 110 mg/kg in oil (Ref. 5.1.). For fish the LC50
value is 0.001-0.003 ppm (Ref. 5.2.).
There are reports of workers becoming ill from inhalation of dust from endosulfan. Symptoms of slight nausea, confusion, excitement, flushing and
dry mouth were experienced (Ref. 5.3.). Also, endosulfan is a central nervous system
stimulant for which no specific antidote is available (Ref. 5.1.).
Accordingly, a TLV of 0.1 mg/m3, as a time-weighted average, is recommended for endosulfan (Ref. 5.3.).
1.1.3. Potential workplace exposure
No estimate of worker exposure to endosulfan could be found. Endosulfan is a broad spectrum insecticide for control of vegetable, fruit, field
crop, and ornamental pests (Ref. 5.1.).
1.1.4. Physical properties (Ref. 5.1. and 5.3.)
Molecular weight: |
406.95 |
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Molecular formula: |
C9H6CL6O3S |
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CAS #: |
115-29-7 |
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Specific gravity: |
1.735 at 20 °C |
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Melting point: |
70-100 °C |
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Solubility: |
Insoluble in water; soluble in xylene, kerosene, chloroform, acetone, and alcohol; decomposes in the presence of acids and
alkalies to form sulfur dioxide. |
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Chemical name: |
6,7,8,9,10,10-hexachloro-
1,5,5a,6,9,9a-hexahydro-6,9-
methano-2,4,3-benzodioxathiepin
3-oxide |
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Synonyms: |
Thiodan, Benzoepin, Cyclodan, Beosit,
Endocel, Chlorthiepin, Crisulfan, Endosan, Endosol,Hildan, Insectophene, Malix, Thifor,
Thimul, Thiofor, Thionex, Tiovel |
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Structure: |
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Description: |
Technical endosulfan is a tan, semi-waxy solid that is a mixture of two isomers with an odor of hexachlorocyclopentadiene and may
have a slight sulfur dioxide odor. |
1.2. Limit defining parameters
The detection limit of the analytical procedure is 13.5 pg
per injection. This is the amount of analyte which will give a peak whose height is
approximately five times the baseline noise. (Figure 1)
2. Sampling procedure
2.1. Apparatus
2.1.1. Samples are collected by using a personal sampling pump that can be calibrated to within ±5% of the recommended flow rate with the sampling device in line.
2.1.2. Samples are collected with OVS-2 tubes, which are
specially made 13 mm O.D. glass tubes that are tapered to 6 mm O.D., packed with 140-mg
backup section and a 270-mg sampling section of cleaned XAD-2 and a 13-mm glass fiber
filter. The backup section is retained by two foam plugs and the sampling section is
between one foam plug and the glass fiber filter. The glass fiber filter is held next to
the sampling section by a polytetrafluoroethylene (PTFE) retainer.
2.2. Reagents
None
2.3. Sampling technique
2.3.1. Attach the small end of the sampling tube to the
sampling pump with flexible plastic tubing such that the large front section of the
sampling tube is exposed directly to the atmosphere.
2.3.2. Attach the sampler vertically in the employee's
breathing zone in such a manner that it does not impede work performance.
2.3.3. After sampling for the appropriate time, remove the
sampling device and seal the tube with plastic end caps.
2.3.4. Wrap each sample end-to-end with an OSHA seal (Form
21).
2.3.5. Submit at least one blank for each set of samples.
Handle the blank in the same manner as the samples, except no air is drawn through it.
2.3.6. Record the air volume (in liters of air) for each
sample, and list any possible interferences.
2.3.7. Submit bulk samples for analysis in a separate
container.
2.4. Desorption efficiency
Six OVS-2 tubes were each liquid spiked with 15 µL of a
422 µg/mL endosulfan standard. The tubes were stored in a drawer overnight at room
temperature. The next day the samples were desorbed in 3 mL of toluene by rotating them
for 60 min and then analyzed. The results are listed in table 2.4.
Table 2.4.
Extraction Efficiency
|
Amount |
Amount |
% |
Sample # |
Spiked, µg |
Found, µg |
Recovered |
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Ex1
Ex2
Ex3
Ex4
Ex5
Ex6 |
6.33
6.33
6.33
6.33
6.33
6.33 |
5.40
5.19
5.47
5.16
5.30
5.36 |
85.3
82.0
86.4
81.5
83.7
84.7 |
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Average = 83.9 |
2.5. Retention efficiency
Five OVS-2 tubes were liquid spiked with 15 µL of a 422
µg/mL standard and humid air (~80% relative humidity) was drawn through
each tube at 1 L/min for 60 minutes. The tubes were stored in a drawer overnight at room
temperature. The next day the tubes were desorbed with 3 mL of toluene by rotating them
for 60 min and then analyzed. The results are listed in table 2.5.
Table 2.5.
Retention Efficiency
|
Amount |
Amount |
% |
Sample # |
Spiked, µg |
Found, µg |
Recovered |
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R1
R2
R3
R4
R5 |
6.33
6.33
6.33
6.33
6.33 |
5.68
5.85
5.65
5.59
5.36 |
89.7
92.4
89.3
88.3
84.7 |
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Average = 88.9 |
2.6. Sample storage
Twelve tubes were liquid spiked with 15 µL of a 422 µg/mL
standard and humid air (~80% relative humidity) was drawn through each
tube at 1 L/min for 60 minutes. Six of the samples were stored at ambient temperature in a
drawer, and six were stored in a refrigerator. After four days of storage, three samples
from each group were desorbed with 3 mL of toluene by shaking for 60 min and then
analyzed. The remaining samples were desorbed and analyzed after seven days of storage.
The results are given in the tables below.
Table 2.6.1.
Ambient Storage
|
Amount |
Amount |
% |
Sample # |
Spiked, µg |
Found, µg |
Recovered |
|
4
4
4
7
7
7 |
6.33
6.33
6.33
6.33
6.33
6.33 |
6.08
5.72
5.77
5.99
5.74
5.41 |
96.0
90.4
91.2
94.6
90.7
85.5 |
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Average of 4 days = 92.5 |
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Average of 7 days = 90.3 |
Table 2.6.2
Refrigerated Storage
|
Amount |
Amount |
% |
Sample # |
Spiked, µg |
Found, µg |
Recovered |
|
4
4
4
7
7
7 |
6.33
6.33
6.33
6.33
6.33
6.33 |
6.08
5.85
5.48
5.67
5.77
5.69 |
96.0
92.4
86.8
89.6
91.2
89.9 |
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Average of 4 days =
91.7 |
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Average of 7 days =
90.2 |
2.7. Recommended air volume and sampling
rate
2.7.1. The recommended air volume is 60 L.
2.7.2. The recommended flow rate is 1.0 L/min.
2.8. Interferences
It is not known if any compounds will interfere with the
collection of endosulfan.
2.9. Safety precautions
2.9.1. Attach the sampling equipment in such a manner that
it will not interfere with work performance or employee safety.
2.9.2. Follow all safety practices that apply to the work
area being sampled.
3. Analytical procedure
3.1. Apparatus
3.1.1. A balance capable of weighing to the nearest tenth
of a milligram. A Mettler HL52 balance was used in this evaluation.
3.1.2. Mechanical rotator.
3.1.3. A gas chromatograph (GC) equipped with an electron
capture detector (ECD). A Hewlett Packard 5890 was used in this evaluation.
3.1.4. A GC column capable of separating endosulfan from
any interferences. A 10 m × .32 mm i.d. (1.0 µm film) DB-5 column was used in this
evaluation.
3.1.5. An electronic integrator, or some other suitable
method for measuring detector response. The Hewlett-Packard 3357 Laboratory Data System
was used in this evaluation.
3.1.6. Volumetric flasks and pipets.
3.1.7. Vials, 4-mL with PTFE-lined septum.
3.1.8. Vials, 2-mL suitable for use on GC autosamplers.
3.2. Reagents
3.2.1. Toluene high purity Burdick and Jackson.
3.2.2. Endosulfan EPA 3180 97.6% purity.
3.2.3. Hexachlorobenzene, reagent grade.
3.2.4. Desorbing solvent, hexachlorobenzene (2µg/mL) in
toluene
3.3. Standard preparation
Prepare stock standards by weighing 10 to 14 mg of
endosulfan, placing in 25-mL volumetric flasks, and diluting to volume with toluene. Make
working range standards by pipet dilutions of the stock standards with the desorbing
solvent. Store stock and dilute standards in a freezer.
3.4. Sample preparation
3.4.1. Transfer the glass fiber filter and large section of
the adsorbent of each sample to a 4-mL vial. Place the separating foam plug and small
section of adsorbent of each sample in a separate 4-ml vial.
3.4.2. Pipet 3.0 mL of desorbing solvent into each vial and
seal with a Teflon-lined septum.
3.4.3. Rotate the vials for 60 minutes.
3.5. Analysis
3.5.1. Instrument conditions
Column: |
DB-5, 1.0 µm film, 10 m × 0.32 mm i.d. |
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Injector temperature: |
235 °C |
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Column temperature: |
170 °C |
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Detector temperature: |
300 °C |
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Gas flows: |
Column 8.6 mL/min hydrogen
Make up 42 mL/min nitrogen |
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Injector volume: |
1.0 µL |
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Split ratio: |
5:1 |
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Retention time: |
10.3 min endosulfan I
15.6 min endosulfan II |
3.5.2. Chromatogram (see Figure 2)
3.6. Interferences
3.6.1. Any collected compound having a similar retention
time and responds to an ECD is an interference.
3.6.2. GC conditions may be varied to circumvent an
interference.
3.6.3. Retention time alone is not proof of chemical
identity. Analysis by an alternate GC column and confirmation by mass spectrometry are
additional means of identification.
3.7. Calculations
3.7.1. A calibration curve (figure 3) is constructed by
plotting detector response versus standard concentration. The detector response is the
value calculated from an internal standard method that sums the areas of the endosulfan I
and endosulfan II peaks.
3.7.2. The concentration of endosulfan in a sample is determined from the calibration curve.
3.7.3. The air concentration is then determined by the following formula.
mg/m3 = |
(µg/mL in sample) × (extraction volume in mL) (air volume in liters) × (desorption efficiency) |
3.8. Safety precautions
3.8.1. Avoid skin contact and air exposure to endosulfan.
3.8.2. Avoid skin contact with all solvents.
3.8.3. Wear safety glasses at all times.
4. Recommendations for further study
The method should be fully validated.
Figure 1
Chromatogram at the Detection Limit
Figure 2
Chromatogram of Endosulfan
Figure 3
Calibration Curve
5. References
5.1. Farm Chemicals Handbook; Meister Publishing:
Willoughly, Ohio, 1986, p C97.
5.2. Kirk-Othmer Encyclopedia of Chemical Technology; John Wiley & Sons: New York, 1981, Volume 13, PP 435-7.
5.3. Documentation of Threshold Limit Values and Biological Exposure Indices; American Conference of Governmental Industrial Hygienists
Inc., Fifth Edition, 1986, p 230.
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